It is one of the few books which could be said to have "made Saints".
However, one reservation is that the ideals in it are to be pursued without excuses, but on some occasions, they may not be possible entirely in one's state of life. For that, I recommend people read Introduction to the Devout Life which was written for all states of life.
Too often, people will think holiness is for "other people" and that one is not actually called to follow Christ in truth. But I think everyone, including oneself, will be surprised that the difficulties in changing oneself is just in the choice to change, and that actually being different is easy and joyful.
For example, giving up a particular thing like TV or video games will be met with mental resistance, but actually giving them up and living without them is incredibly easy. The same is true of more spiritual changes. The human weakness is to maintain whatever one has, and to justify it, rather than to convert and imitate Christ.